
Pathfinder DVL Guide
April
2018
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Page 109
#BM – Bottom Mode
Purpose:
Sets the Bottom Track mode.
Format:
#BMn
The BM commands work with or without the # sign. For example, using BM or #BM are both
valid commands.
Range:
n = 8, 9, or 101
Default:
#BM8
The default setting for this command is recommended for most applications.
Description:
Bottom Mode 8 was developed for the following improvements in shallow operations:
•
Much improved accuracy by pinging Beams around, one at a time.
•
Better handling of slopes by independently setting lags on each beam based on accurate bottom
detection before each ping.
•
Better handling of station keeping application using longer lag.
•
Higher resolution Bottom Detection using short lag Bottom Feeler pings.
Table 22:
BM8 Minimum Tracking Depths
Frequency
Min Tracking Depths
With Low Altitude feature
600KHz
0.2m
<20cm
Bottom Mode 9 is identical to Bottom Mode 8 except that it does not have a shallow mode.
#BM101 enables the Side-Lobe coupling test. Note that this command doesn’t work in the non-# version
of the menu, it’s expert-only.
#BN - Speed Log Hold/Drop Control
Purpose:
Controls the behavior of the distance measure calculation when Bottom Track is lost.
Format:
#BNx,y
The BN commands work with or without the # sign. For example, using BN or #BN are both
valid commands.
Range:
x = 0 to 1
y = 0 to 999 seconds
Default:
#BN0,999
The default setting for this command is recommended for most applications.
Description:
The #BN command governs the behavior of the earth referenced distance measurement
calculation in the
PD6
data format when the Pathfinder can’t get a lock on the bottom. The
y parameter represents a timeout period during which zero is used for the current veloc-
ity measurement in the equation shown in the #BO command. After the expiration of the
y timeout, the behavior is governed by the x parameter. If x is zero, then the accumulated
distance is set to zero. If x is one, then the accumulated distance is maintained at its cur-
rent value until the Pathfinder achieves bottom lock.